Operating device for anti-skid devices for vehicles

ABSTRACT

An anti-skid mechanism operating device includes an operating unit and an operating arm pivotally supported thereby and intended to carry a rotary anti-skid and to operate the latter between an active position and a passive position. The operating unit is formed with a linear drive and a rotationally mounted rotary device, which is connected to the operating arm. A string-like drive transmission element extends essentially along the longitudinal axis of the drive, between the drive and the rotary device, in order to translate a linear movement of the drive into a pivotal movement of the operating arm in two opposite directions.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/SE99/00107 which has an Internationalfiling date of Jan. 27, 1999, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to an operating device for anti-skiddevices.

PRIOR-ART TECHNOLOGY

Automatically operating anti-skid devices generally comprise anoperating unit and an operating arm pivotally carried by said unit. Ananti-skid means, usually a roller, to the periphery of which is attacheda number of anti-skid elements in the form of short pieces of chain, isrotationally mounted on the operating arm. By pivoting the operating armthe anti-skid means may be shifted between an active position, in whichthe roller abuts against the side face of a vehicle wheel so as to berotated thereby and to throw pieces of chain in between the wheel and asupport, and a position of rest, wherein the roller is spaced from thewheel and lifted to a position underneath the vehicle.

When anti-skid devices of this kind are used it is important that therotary anti-skid means abuts against the vehicle wheel at exactly theright place. It has also been found that the angle of the rotatinganti-skid means in contact with the vehicle wheel relative to the planeof rotation of the vehicle wheel determines the degree of anti-skideffect that it is possible to obtain.

In the position of rest of the anti-skid device, the rotary anti-skidmeans must be shifted to a suitable location underneath the vehicle andspaced from the road surface as well as from the vehicle wheel.

Anti-skid devices of the kind to which the present invention relatesgenerally are mounted on the rear axle of heavy-duty vehicles. Inheavy-duty vehicles, considerable differences of appearance exist as tothe configuration and design of the mounting place and the rear-axlearea. Furthermore, the tolerances as to the design and the position ofthe rear axle are considerable in this type of vehicle. Consequently, itbecomes necessary to mount the anti-skid device in a different manner ineach vehicle model. For each discrete mounting instance the anti-skiddevice also needs to be set individually in order for the rotaryanti-skid means to be correctly located in the active as well as in thepassive position.

Particular difficulties are experienced in anti-skid devices that are tobe mounted on buses and smaller vehicles because of the extremelyreduced space available. This problem is felt to an increasing extentalso in heavy-duty vehicles, since in modern trucks the available spacearound the rear axle tends to become increasingly smaller. Consequently,high demands are placed on anti-skid devices to be as small as possible.

EP-A-162 823 describes an anti-skid device of the kind defined above,wherein the operating unit comprises an air cylinder which isremote-connected to the operating arm via a lever and a first wire inorder to pivot said arm to the active position by transmission oftraction via the wire. A return spring is connected to a second wire,which in turn is connected to the operating arm in order to bias thespring, when the arm assumes the active position. Return of theoperating arm to the position of rest deactivates the air cylinder,whereupon the return spring resets the operating arm to the position ofrest by transmission of traction via the second wire.

A wire construction of this nature is sensitive to the salty and moistenvironment prevailing wintertime in the area of the vehicle chassis. Inconstructions of this kind, problems frequently arise from corrosiveattacks on the wires, making them stick or rust away. In addition,stretching of the wires due to tensile stress is a possibility that alsomust be taken into consideration.

EP-B-278 896 describes an operating unit for anti-skid devicescomprising a drive means in the form of an axially movable rack inengagement with a pinion, the latter in turn connected to the operatingarm in order to pivot the latter. The pinion is arranged centrallyrelative to the area of movement of the rack and is located on the sameshaft as the operating arm, for which reason also the operating arm isarranged centrally relative to the area of movement of the rack. Similarconstructions are described also in EP-A-487 297 and EP-A-443 455.

A problem encountered in rack/pinion combinations of this kind is thatthey are complicated and consequently expensive to manufacture and tomaintain. Another drawback found in these constructions is that theyreduce the space available to the designer in positioning the operatingunit underneath a vehicle because of the central location of theoperating arm relative to the area of movement of the rack, for whichreason it is difficult to position the operating device close to anothercomponent underneath the vehicle, which is often necessary.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an operating devicefor anti-skid devices, which is greatly improved over the prior-artsolutions described above.

One particular object is to provide an operating unit, which isincorporated in the device and gives the designer considerable freedomin positioning the unit on the bottom face of the vehicle.

These and other objects, which will appear from the followingdescription, have now been achieved according to the teachings of theinvention by means of an operating device of the kind defined in theintroduction hereto.

Thus, a rotary means, arranged to rotate about a rotational shaft, isconnected to a linear drive means, the force of which is exerted in thedirection along a longitudinal axis, by means of a string-like drivetransmission element in order to translate a linear movement of thedrive means into a pivotal movement of an operating arm. The drivetransmission element extends essentially along the longitudinal axis ofthe drive means between the drive means and the rotary means in order totransmit motion in two opposite directions between the drive means andthe rotary means.

The drive transmission element is non-rotationally connected to therotary means, i.e. it is securely attached to the rotary means in theperipheral direction, like, for example, a chain engaging a toothedwheel or a wire tightly lapping a wheel.

In this manner an operating device is provided, wherein the movement ofa linear drive means may be translated into a rotational movement of arotary means without the linear drive means having to extend past therotary means on two sides of the latter. This makes it possible toinstall the rotary means in one end area of the operating unit and toconnect one end of the operating arm directly to the rotary means, andconsequently the operating unit may easily be placed in a convenientposition underneath a vehicle, since the operating unit essentiallyextends in one single direction, from the point of attachment of theoperating arm. This direction may be chosen optionally in adaptation tothe individual configuration of different vehicles. The opposite end ofthe operating arm, i.e. the one spaced from the rotary means and thedrive transmission element, may support an anti-skid means.

In addition, the operating arm may be pivoted within a large angularrange without requiring additional space in more than one direction.

Because the drive transmission between the drive means and the rotarymeans is produced by a string-like means instead of by direct meshing ofteeth on drive means and drive transmission means, respectively, itbecomes possible to manufacture the operating unit at a lower cost thanhitherto, due to the fact that the drive and rotary means need no longerbe formed with a plurality of directly meshing toothed sections thatneed to be produced to a high degree of precision.

In accordance with a preferred embodiment the drive means act along alongitudinal axis essentially perpendicular to the rotational axis ofthe rotary means.

In accordance with another preferred embodiment, the drive transmissionelement is formed with a first portion, which is coupled to the drivemeans, and with a second portion, which is coupled to the rotary means.

In accordance with yet another preferred embodiment of the invention thedrive transmission element extends in a continuous loop around therotary means and around a deflector means, about which the drivetransmission element is arranged to move. In a simple manner, thisarrangement enables the drive transmission element to absorb motion intwo opposite directions of movement without the element in itself havingto be able to absorb compressive forces. Consequently, simpletraction-absorbing drive transmission elements may be used, which iseconomically advantageous.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described in more detail in the following withreference to the accompanying schematic drawing, which for exemplifyingpurposes shows a presently preferred, not restricting embodiment of theinvention.

FIG. 1 is a schematic plan view of an anti-skid device having ananti-skid means positioned in close vicinity to a vehicle wheel.

FIG. 2 is a sectionalised view taken on line II—II in FIG. 1 of anoperating device for an anti-skid device.

FIG. 3 is a sectionalised view of the operating unit, the view beingtaken on line III—III in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

Reference is made in the following to FIG. 1, which shows a preferredembodiment of an anti-skid device 1 mounted at a schematicallyrepresented vehicle wheel 5 of a motor vehicle. The anti-skid device 1comprises an operating device including an operating unit 10 and anoperating arm 6, which is pivotally supported by the operating unit 10,and an anti-skid means 2, which is rotationally mounted on the arm 6 andwhich comprises a roller 3 and a plurality of anti-skid elements in theform of pieces 4 of chain which are attached to the periphery of theroller 3. The operating arm 6 thus extends between the operating unit 10and the anti-skid means 2.

By means of the operating unit 10, the operating arm 6 may be activatedto perform a pivotal movement, shown by the double arrow 7, between anactive position, as illustrated, and a position of rest. In the activeposition, the periphery of the roller 3 is in contact with the side faceof the vehicle wheel 5, and consequently the roller 3 is rotated in thedirection of arrow 8, throwing pieces 4 of chain in front of the vehiclewheel 5, between the latter and the road surface, when the vehicletravels in the direction of arrow 9. In the passive position (notshown), the anti-skid means 2 has been transferred away from the vehiclewheel 5 and the road surface to a suitable position underneath thevehicle.

The operating unit 10 will be described in closer detail in thefollowing with reference to FIGS. 2 and 3. The operating unit 10comprises a drive unit 12 and a transmission unit 13, which are enclosedin a drive unit housing 11 a and in a transmission unit housing 11 b,respectively, together forming a housing 11.

The drive unit 12 comprises a compressed-air cylinder 20 having a pistonmeans 22 acting linearly along a longitudinal axis B, to thus form adrive means. The piston means 22 comprises a piston rod 24 protrudinginto the interior of the transmission unit 13. The compressed-aircylinder 20 is a double-acting cylinder, i.e. it is capable of drivingthe piston means 22 in both directions along the longitudinal axis B.

The transmission unit 13 is formed with a rotary means 30 extendingalong the longitudinal axis B and comprising a shaft 32, which ismounted for rotational movement about a rotational axis A, and a wheel34, which is non-rotationally mounted on the shaft 32 and which isarranged to rotate in a rotational plane coinciding with thelongitudinal axis B. In addition, the transmission unit 13 is fittedwith a pulley 36, likewise mounted in the housing 11. A string-shapedand non-stretch drive transmission element, in the subject case a drivetransmission chain 40, extends in a continuous loop around the rotarymeans and the pulley 36 and is connected to the end portion of thepiston rod 24. The chain 40, the links of which are able to flexrelative to one another, also is non-rotationally attached to theperiphery of the wheel 34 and extends along a straight line, in parallelwith the longitudinal axis B and close to the extension of the pistonrod 24, when the latter assumes its position of maximum penetration intothe transmission unit 13. As a result, the rotary means 30 will berotated, as the piston means 22 is being displaced in its longitudinaldirection B. As appears from FIG. 2, one end of the operating arm 6 isnon-rotationally connected to the shaft 32 on the external face of thehousing 11, for which reason the piston means 22, when displaced, willcause the arm 6 to perform a pivotal movement. The anti-skid means 2,mounted at the opposite end of the operating arm 6, spaced from therotary means 30 and the drive transmission element 40, then is movedtowards or away from the vehicle wheel 5. The radius of the wheel 34determines the gear ratio between the movement of the drive means 22 andthe movement of the operating arm 6.

The pulley 36, which is located in close vicinity to the drive means 22in order to guide the chain 40 between the pulley 36 and the piston rod22, can be formed with a small-size diameter, when the drivetransmission element is a chain having mutually flexible links, afeature which contributes to the possibility of designing the operatingunit as a compact-size means.

The transmission unit housing 11 b, which encloses the transmission unit13, efficiently protects the components of the latter from the effectsof the environment. FIG. 2 also shows a holding member 15, which ismounted on the housing 11 and which is intended for attachment to thevehicle in order to keep the operating unit stable.

The chain 40 comprises a first portion 41, which is fitted with afastening means in the form of a fastening plate 44 forming part of alink of the chain 40 and being attached to the piston rod 24 by means ofscrews or some other suitable means. A second portion 42 of the chain 40is formed with a corresponding fastening means including a link having afastening plate 46, which is attached to the periphery of the wheel 34.Such drive-transmitting connections may also be achieved in some othersuitable manner, such as for example by means fitting the wheel 34and/or the piston rod 24 with teeth in engagement with the links of thechain 40. The solution appearing from the drawing figures is, however,advantageous from a manufacturing point of view, inasmuch as smoothwheels are easier and cheaper to manufacture than toothed wheels.

In accordance with the invention the string-like drive transmissionelement 40 is capable of transferring motion between the drive means 22and the rotary means 40 in two opposite directions (double arrow 26 ofFIG. 3) in the longitudinal direction B. In accordance with analternative embodiment, such transmission could be achieved withoutelement 40 being configured as a continuous traction absorbing loop. Thedrive transmission element 40 could, for example be configured as apiece of string extending from the drive means 22 in the longitudinaldirection B thereof to the periphery of the rotary means 40 and being initself capable of absorbing traction as well as compressive forces, forexample a chain the links of which may turn in one direction only.However, also in this case the drive transmission element is arranged toflex in at least one direction in order to be able to adapt itself tothe periphery of the rotary means as the latter is moving.

In accordance with one aspect of the invention, the chain 40 forms adrive-transmitting prolongation of the drive means 22, whichprolongation is deflected laterally around the rotary means 30, thusrequiring space in the longitudinal direction B only to one side of therotary means 30. In this case, the drive means 22 is located spaced fromthe rotary means 30 in a first end position and in a second end positionit extends closer to or up to the rotary means 30. The prolongation ofthe longitudinal axis B then is in parallel with the drive-transmittingpart of the chain.

In accordance with the shown embodiment, the compressed-air cylinder 20is of the double-acting type without any spring means being connectedthereto. Consequently, the dimensions of the compressed-air cylinder 20may be small, since no return spring force need to be overcome, whichfurther increases the freedom of choice in the mounting of the anti-skiddevice. A return spring of the heavy kind usually used in anti-skiddevices in itself constitutes safety risk during mounting andmaintenance work.

Finally, it should be pointed out that the invention should not in anyway be regarded as limited to the embodiment described herein but thatmodifications are possible within the scope of the inventive idea asexpressed in the appended claims.

For example, the invention is applicable to linearly acting drive meansthat are operated by other power sources than compressed air. Inaddition, a return spring may be connected to the drive means, shouldthis be desirable in some situations. The drive-transmission elementneed not be a chain but could be formed by any other string-like meansthat is able to transfer motion in its longitudinal direction. Inaddition, the inventive concept is applicable to the illustrated type ofanti-skid means incorporating a roller as well as to other types ofrotary anti-skid means.

What is claimed is:
 1. An operating device for anti-skid devices forvehicles, comprising: an operating unit, and an operating arm forsupporting at an end spaced from the operating unit a rotary anti-skidmeans, said operating arm being pivotally mounted on the operating unitfor movement between an active position and a rest position, saidoperating unit including: a linear drive acting along a longitudinalaxis, a rotary rotatable about a rotational axis, a deflector, and adrive transmission element extending in a continuous loop around therotary and the deflector, and extending essentially along thelongitudinal axis of the drive between the drive and the rotary, saiddrive transmission element being arranged to translate linear movementof the drive in two opposite directions into rotational movement of therotary, said rotational movement producing a pivotal movement of saidoperating arm between the active position and the rest position.
 2. Theoperating device as claimed in claim 1, wherein the rotational axisextends essentially perpendicular to the longitudinal axis.
 3. Theoperating device as claimed in claim 1, wherein the rotary is rotatablein a rotational plane, which is essentially parallel with thelongitudinal axis of the drive means.
 4. The operating device as claimedin claim 1, wherein the drive transmission element is at least partlyflexible in at least one direction.
 5. The operating device as claimedin claim 1, wherein the drive transmission element is a chain havinglinks, the links being flexible relative to one another.
 6. Theoperating device as claimed in claim 5, wherein traction and compressiveforces are transmittable by the transmission element.
 7. The operatingdevice as claimed in claim 1, wherein the drive transmission element isanchored to a peripheral part of the rotary.
 8. The operating means asclaimed in claim 1, wherein the operating unit is of an elongatedconfiguration, said rotary means being located in an end portion of saidoperating unit.
 9. The operating device as claimed in claim 1, whereinthe drive is a compressed-air piston located in a compressed-aircylinder and having a piston rod connected to said drive transmissionelement.
 10. The operating device as claimed in claim 1, wherein thedrive, the drive transmission element, and the rotary are enclosed in ahousing.
 11. An anti-skid device for motor vehicles which is fitted withan operating unit in accordance with claim
 1. 12. A motor vehicle whichis fitted with an anti-skid device